Effect of two different storage temperatures (-12 ⁰C and -20 ⁰C) on the proximate and microbial quality of Labeo rohita muscles

Abstract

The present study was aimed to investigate the proximate and microbial profile of muscles of Labeo rohita kept under storage at two different temperatures viz. -12 ⁰C and -20 ⁰C for a period of 4 weeks. The analysis was carried out at an interval of 7 days. Initially, the proximate composition of fresh samples (at 0 day) revealed 16.00±0.1% protein, 3.55±0.01% lipid, 82. 28±0.04% moisture and 1.45±0.04% ash. However, after 4 weeks of frozen storage, there was a significant percentile decrease (p≤0.05) i.e. 36%, 60.2%, 8.53%, 27.5% in protein, lipid, moisture and ash content, respectively in -12 ⁰C storage samples and in -20 ⁰C storage sample the percentile decrease was comparatively less, i.e. 17.87% in protein, 24.50% in lipid, 5.28% in moisture and 20.68% in ash. The microbial load of fresh samples was found to be 2.10±0.2 log cfu/g (TPC i.e. Total Plate Count), 1.20±0.15 log cfu/g (CC i.e. Coliform Count), 2.12±0.02 log cfu/g (PC i.e. Psychrophilic Count). These values increased significantly (p≤0.05) during 4 weeks of frozen storage. The study further revealed that, TPC was within the acceptable limit (6 log cfu/g) on 21st day in samples stored at -20 ⁰C whereas at -12 ⁰C it crosses the limit on 7th day of storage, beyond which the quality of fish deteriorates thus, making it unfit for human consumption. Thus, storage of fish fillets at -20 ⁰C extends their shelf life by 2 weeks as compared storage at -12 ⁰C.